Reticulate foil and its aperture shape for electric dry shaver

ABSTRACT

The invention relates to an electric dry shaver, and more particularly to the construction of the reticulate foil used by said electric dry shaver, the aperture shape and its arrangement.

United States Patent (191 Yamaoka July 3, 1973 I [22] Filed:

[541 RETICULATE son. AND ITS APERTURE SHAPE r0: ELECTRIC DRY smvau [75] Inventory Goichi Yaln aoltmokayarhpan" [73]- Assignee: Kabushild Kakha Suwa Seikasha, Tokyo, Japan Aug. 24, 1970 [21] Appl. No; 66,516

[30] Foreign Application Priority w.

Sept. l2, I969 Japan".. 44172163 521 u.s.c|. 30346.61, 30/3465! 511 Int. Cl. ..B26b 19/04 [58] Field otSearch 30l346.5l.- 346.61, I 301346.57

[56] 7 References Cited UNITED STATES PATENTS 3.602.991 9/ I971 Heinrich 30/3465] 2,198,833 4/1940 Muros. 301346.5IX

3.093.899 15/19633 Fi'itt'erer 30/3465! X Primary Examiner-Andrew Juhasz 4mm": Examiner-Gary L. Smith Anomey-Blum, Moscovitz, Friedman & Kaplan [5.7 1 ABSTRACT The invention relates to an electric dry shaver, and

morefp'articul'arly to the construction of the reticulate foil used by said electric dry shaver, the aperture shape and its arrangement. I

.3 cm, 7 Drawing Figures RETICULATE FOIL AND ITS APERTURE SHAPE FOR ELECTRIC DRY SHAVER BACKGROUND OF THE INVENTION In general, the reticulate foil for an electric dry shave! is composed ofv thin metal having many haircuttir g apertures. Said foil introduces a hair and cuts it i boperatien with t i r a Th s, the u ctien o an fo i the mo f am n al f r h ving and determines the shaving efficiency. The main elements construction of said foil, which determines the shaving efficiency, are as follows;

SUMMARY OF THE INVENTION Shape and size of the cutting aperture; method of its arrangement; Opening ratio of the reticulate foil; and the thickness of the foil. When all of these elements are suitable, shaving efficiency is most favorable. Generally, good shaving requires cutting hair short, fast and smoothly as far as possible without injuring the skin by t e nne blade.

According to the invention, the opening ratio is increased by means of suitable shape and size of the cutting aperture and method of its arrangement as stated above: Therefore, a hair is introduced into the aperture very fast, it being advantageous that the hair only is inserted deeply into, the aperture by means of a special Putt n pe ture s apewo ld t u e Po ible t shave. without injuring the skin by the inner blade. The

POint of the invention intends to for ch-type eonvexity respectively at the inner hree points which divide the aperture into. equal parts, and arrange those apertures in such. a manner that the bridge width of the reticulate foil: is constant.

BRIEF DESCRIPTION OF THE DRAWINGS;

FIG. I shows the most favorable and effective aper-v u e s ap ccording; t t nv nt o FIG. 2 is a sectional view showing themost effectivearrangementof the apertures, the shape of which ishqwn n F G- FIG, 3; shows the part of thearrangement of the circular aperture shapes which are the most popular shapes at present;

FIG. 4 shows, part of the arrangement. of the hexagonal apertures. shown in.U.S. Pat. No. 3,093,899;

FIG. 5 is asectional view showing that the skin also enters ina conventionalcutting aperture together with a hair;

FIG. 6 is a cross sectional view showing that'only: a. hair enters into a cutting aperturein accordance. with.

The following explains in detail the object of the, in-.

vention by, means. of :oneembodiment shown in the drawings, comparedwith the conventional aperture shape. of the reticulate .foil.

According to the invention, the. most convenient and;

concrete apertureshape is shown. in FIG. 1, its arrangement being. shown in FIG. 2. In FIG. 2, the apertures have threearch-type convexities and are. arranged. so that the, bridge width. 3 between; the apertures harev kept constant.

The arrangement is such that the bridge width 3 between the apertures is kept constant and to arrangethe cutting apertures most effectively on the foil. Also, said arrangement is the fundamental element necessary to increase the opening ratio of the foil. Therefore the cutting efficiency is heightened and the hair is inserted more quickly because of said arrangement. The constant width of the foil bridges assures the same strength over the entire surface of the foil, so that while the opening ratio is high, the foil is strong.

The circular aperture shape, shown in FIG. 3, is in Wide use at the present time. The bridge width 6 of said circular aperture is low. The hexagonal aperture, shown in U.S. Pat. No. 3,093,899, makes the opening ratio higher and is the most practical. The arrangement of said hexagonal aperture is shown in FIG. 4 of the invention.

The aperture shape and its arrangement according to the present invention provides an equal or higher opening ratio to the hexagonal aperture. Moreover, compared with the hexagonal aperture, the aperture'shape of the present invention is more efficient in cutting the hair as. short as possible without injuring the skin by the inner blade.

In order to cut the hair as short as possible, it is necessary to insert the hair deeply into a cutting aperture as shown at 15 in FIG. 5 and 1 in FIG. 6. For this purpose the aperture 1 is made larger and the foil is made thinner. If the-aperture is made too large or the'foil is made too thin, not only the hair but also the skin is inserted. into the aperture, as in FIG. 5 thus injuring the skin by the inner blade and reducing the shaving efficiency. The present invention, however, provides a unique aperture shape shown in FIG. 1, into "which the hair alone is deeply inserted without injuring the skin by the inner blade. The outline concerning this'aperture shape has been mentioned above, and the effectiveness; ofsaid aperture shape during shaving is explained below.

According to the invention, the most favorable aper-' complished by means of forming convexities 2 at the inner side of the circular aperture.

According to the invention, the circle 4, which passes three. peaks a, b, c of the convexities 2, is imagined. Considering said imaginary circle 4 as the cutting aperture, the peaks a, b, and c are arranged on said cutting.

which passes the three points d, e, and f in FIG. 1. The

size of said circle 1 l is determined so that the hairis inserted easily, and is larger than that of the circular ap erture of the foil having proper size circular apertures.

Byapplying stronger pressure to the foil during shaving, only the root of the hair is inserted into the aperture as shown in FIG. 6 due to the peaks a, b, and c. At

the'sametime, the-skin 12, which has been pushed out by thepeaks a, b, and c, is pushed away into the concavityz5. If the electric dry shaver is moved over the skin for shaving, the root of the hair, being pushed out, is moved in an instant to the cutting foil 13 which is shown by the thick lines in FIG. 1. The hair is then cut by said cutting foil 13 and the inner blade.

In the aperture shape of the foil of the invention, in order to raise the shaving efficiency, changing the aperture shape" somewhat may be readily accomplished according to the type of inner blades, their efficiency, the thickness of the hair and the strength of the skin. In FIG. 1, by means of changing the dimensions X and Y, (changing the size of three convexities 2) it is possible to cut the hair easily under all conditions. For example, in the aperture shape shown in FIG. 7, X is no longer than Y. This shape is suited to shave the longer hair. However, if the difference between X and Y is too great, the bridge width 3 on the foil is not constant, thereby decreasing the opening ratio. As a result, shaving efficiency is reduced. According to the. present invention, the most favorable way is to make the dimensions of X and Y constant. This is the only way to make the arrangement of the apertures most effective. By arranging the said aperture, therefore, the opening ratio becomes highest.

Moreover, by arranging the apertures in such a manner that X is different from Y, the universal shaver for cutting all kinds of hair can be manufactured. According to the invention, said aperture shape can cut the hair effectively without regard to cutting direction of the hair; namely, the position of the hair in the cutting aperture, and moving direction of the inner blade. In FIG. 1, when the inner blade moves in the direction shown by the arrows A, B, and C the hair 7 in the aperture moves to the concavity 5 in an instant (7 after the movement), and is cut down by the foil 13 shown by the thick lines. When the inner blade moves in the direction shown by the arrows D, E, and F, the hair moves first to the convexity 2, then moving to the concavity 5 by means of said arch-type convexity 2 and cut down by the foil 13 shown by the thick lines.

The aperture shape of the invention does not set the cutting direction, so the shaving efficiency is not affected by the moving direction of the inner blade. Therefore, the cutting efficiency is not affected because of such arrangement. The angle of the edge 14 of the cutting foil 13 is comparatively small, so the hair which is inserted into the concavity 5 (for example 7') does not run away from the concavity 5. Moreover, the cutting foil 13 shown by the thick lines is somewhat concave. This prevents the hair from moving and also avoids injuring the skin during shaving.

As described above, the unique aperture shape of the invention cuts the hair shortest without injuring the skin by the inner blade. Saidaperture shape catches the hair effectively, which is introduced into the aperture,

' and cuts the hair in any direction. By arranging said aperture shapes, the opening ratio is greatly increased.

Therefore the most favorable advantage of the invention, i.e. the highest opening ratio provides very fast shaving, comfort and shaving efficiency in cutting the hair short without injuring the skin by the inner blade.

As described in the preceding clauses of this specification, the summary or the basic idea of the invention is to provide arch-type convexities at three points inside the aperture. The effectiveness of said convexities is not affected by the size or the shape of said convexities. There is no special necessity for equalizing the dimension X with Y. In order to maintain constant bridge width, each concave arc in a given aperture must have the same center as the corresponding convex arc in the adjacent aperture. This is evident from FIG. 2. Consequently, each concave arc must be slightly larger than the convex arc in the same aperture.

Furthermore, the invention does not limit the quantity and the position of arch-type convexities 2. However, in order to make our invention most effective and favorable, it is desirable to provide the highest opening ratio by means of equalizing the dimensions of X and Y as far as possible and arrange the convexities 2 as a regular triangle at three points which divide the aperture into three equal parts. Thus the invention provides the excellent shaving efficiency.

What is claimed is:

1. In an electric dry shaver, an improved reticulate foil wherein each aperture is bounded by a total of six alternate convex and concave arcs, so arranged that the width of the bridge between adjacent apertures is essentially constant each bridge being bounded by a pair of said arcs, each said pair of said arcs consisting of one concave and one convex arc, each said pair of said arcs further having the same center of curvature.

2. An improved reticulate foil as defined in claim 1, wherein each aperture has therein six corners, each of said corners being formed by the junction of a convex and a concave arc, each of said corners being adapted for lodgement of a hair therein during use of said shaver, thereby facilitating the operation of shaving.

3. An improved electric dry shaver as defined in claim 1, wherein said apertures lie in a triangular array. l l II! t 

1. In an electric dry shaver, an improved reticulate foil wherein each aperture is bounded by a total of six alternate convex and concave arcs, so arranged that the width of the bridge between adjacent apertures is essentially constant each bridge being bounded by a pair of said arcs, each said pair of said arcs consisting of One concave and one convex arc, each said pair of said arcs further having the same center of curvature.
 2. An improved reticulate foil as defined in claim 1, wherein each aperture has therein six corners, each of said corners being formed by the junction of a convex and a concave arc, each of said corners being adapted for lodgement of a hair therein during use of said shaver, thereby facilitating the operation of shaving.
 3. An improved electric dry shaver as defined in claim 1, wherein said apertures lie in a triangular array. 